1. Field of the Invention
The present invention relates to a driving device for a display device equipped with a matrix electrode structure, and in particular to a driving device for a ferroelectric liquid crystal display device and a display system utilizing the same.
2. Related Background Art
The ferroelectric liquid crystal display devices are driven by multiplexing drive methods as already proposed in U.S. Pat. No. 4,655,561 of Kanbe et al., U.S. Pat. No. 4,638,310 of Arpliffe, U.S. Pat. No. 4,715,688 of Harada et al., U.S. Pat. No. 4,701,026 of Yazaki et al., U.S. Pat. No. 4,725,129 of Kondo et al., and U.S. Pat. No. 4,711,531 of Masubuchi et al.
In these drive methods, a voltage signal of a pulse duration and a peak value sufficient for generating a black or white display state in a pixel of a scanning line is applied within a period selected for scanning. Such voltage signals are applied in succession for each scanning line, and an image frame is formed by repeating such signal supply. Consequently, the above-mentioned driving methods have been associated with a drawback that the frame frequency becomes inevitably lower with the increase in the number of scanning lines.
The above-mentioned drawback has been solved by driving methods proposed in the Japanese Laid-open Patent Sho 60-172029 of Kanbe et al., and the U.S. Pat. No. 4,770,502 of Kitajima et al. In these driving methods, after the pixels of a scanning line are simultaneously erased to the black (or white) display state, signal writing to said pixels is conducted by the application of a writing voltage signal, and at the same time the pixels of a scanning line to be written next are simultaneously erased. These methods allow to increase the frame frequency.
In such methods, the selected periods for two scanning lines mutually overlap in such a manner that, while a scanning line is subjected to a writing operation, the next scanning line is subjected to an erasing operation. Consequently, if there is an interruption display (for example frame display drive, which is a scanning at regular intervals for forming a frame display) or a change in the display conditions due to a temperature change in the course of display drive, such interruption display or change of driving conditions is initiated after a scanning operation so that the scanning line to be selected next remains in the erased state.